<SEC-DOCUMENT>0000807863-19-000002.txt : 20190108
<SEC-HEADER>0000807863-19-000002.hdr.sgml : 20190108
<ACCEPTANCE-DATETIME>20190108111459
ACCESSION NUMBER:		0000807863-19-000002
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20190103
FILED AS OF DATE:		20190108
DATE AS OF CHANGE:		20190108

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DEBELLO JAMES B
		CENTRAL INDEX KEY:			0001212148

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35231
		FILM NUMBER:		19514977

	MAIL ADDRESS:	
		STREET 1:		600 B. STREET
		STREET 2:		SUITE 100
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92101

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MITEK SYSTEMS INC
		CENTRAL INDEX KEY:			0000807863
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER PERIPHERAL EQUIPMENT, NEC [3577]
		IRS NUMBER:				870418827
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		600 B STREET
		STREET 2:		SUITE 100
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92101
		BUSINESS PHONE:		619-269-6800

	MAIL ADDRESS:	
		STREET 1:		600 B STREET
		STREET 2:		SUITE 100
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92101
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_154696406980940.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-01-03</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000807863</issuerCik>
        <issuerName>MITEK SYSTEMS INC</issuerName>
        <issuerTradingSymbol>MITK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001212148</rptOwnerCik>
            <rptOwnerName>DEBELLO JAMES B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 B STREET, SUITE 100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Former CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-01-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>29550</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.12</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>591911</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">In connection with the reporting person's resignation from the Company, 82,123 unvested restricted stock units held by the reporting person were automatically accelerated and became vested pursuant to the terms of the reporting person's Executive Severance and Change of Control Plan. At such time, 29,550 shares were automatically sold by Mitek Systems, Inc. to pay withholding taxes upon vesting of such restricted stock units in satisfaction of such withholding obligations.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Trevor Renfield, by Power of Attorney</signatureName>
        <signatureDate>2019-01-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
